Pathological Process
Pathological process (processus pathologicus) is a predictable, dynamic combination of tissue and organ changes arising in response to injury. Crucially, it encompasses not only pathogenic (destructive) mechanisms, but also adaptive (protective) mechanisms.
- Dynamism: The process is continuously evolving. If the scale and severity of damage escalate, it may progress into a full-blown disease.
- Localization: Unlike a disease as a whole, a process is often restricted to a specific tissue or organ, and its pathogenic impact may be relatively mild (e.g., local soft tissue trauma is better tolerated than systemic post-traumatic illness).
- Stereotypy: Regardless of the etiology, the mechanisms of development involve standard (typical) links.
- Link to Disease: The duration and severity of the pathological process ultimately shape the individual clinical picture of the disease in a given patient (onset features, clinical course, complications, and treatment response).
Pathological Reaction
A pathological reaction is an organism's response to a stimulus that has lost its biological purpose. Such a reaction is always inadequate (quantitatively or qualitatively) and non-adaptive, even when triggered by ordinary, non-pathogenic factors.
Most commonly, it results from impairments in general reactivity or the reactive properties of individual tissues.
Classic Examples:
- Allergic reactions — distorted psychosomatic responses during the development of phase states in the nervous system.
- Phobias — unmotivated, objectively baseless fear of an object or phenomenon.
- Pathological reflexes — situations where irritation in one zone provokes a destructive response in another. For instance, a gallstone reflexively triggers coronary artery spasm and an anginal attack.
Pathological State
If a process is dynamic, a pathological state is stability. It represents a long-term, protracted deviation of structure, biochemistry, or function from the norm, and is entirely devoid of intensive progression.
It arises as a consequence of past pathogenic exposures, diseases, or surgical interventions:
- Cardiac valve deformities (as an outcome of healed endocarditis).
- Post-amputation states, nephrectomy, dental extraction, partial lung or bowel resection.
- Congenital malformations and developmental anomalies (clubfoot, cleft lip, or cleft palate).
Clinical significance lies in the fact that these states act as risk factors for new diseases. Edentulism predictably promotes gastritis, living with a single lung or kidney predisposes to respiratory failure or uremia, and a stenotic heart valve eventually leads to heart failure.
Etiology and Properties of Pathogenic Factors
The term "etiology" is used in pathophysiology in two ways: as the science of the causes of pathologies, and as the designation of the specific cause of a particular disease. The cause itself (a pathogenic, extraordinary, or extreme factor) triggers the disease and imparts specific features to it.
For a factor to be pathogenic, it must possess certain properties:
- Unusual nature: The organism lacks evolutionarily developed defenses against animal venoms, synthetic drugs, electric current, extreme temperatures, or aggressive chemicals (acids, alkalis, heavy metal salts).
- Excess: An excessive amount of normal endogenous substances (catecholamines, free radicals, glucose) or external exposures (barometric pressure shifts).
- Deficit: A shortage of exogenous (oxygen, vitamins, trace elements) or endogenous (hormones, enzymes, cytokines) components.
- Circadian rhythm disruption: Disruption of the sleep-wake and feeding cycles leads to dyschronosis, neurotic states, and peptic ulcer disease.
- Conditioned-reflex fixation: A neutral stimulus (sight of an animal, environment) becomes associated with tissue injury and independently triggers attacks (e.g., in bronchial asthma). This category also includes iatrogenesis — disorders resulting from careless remarks by medical personnel.
- Polypathogenicity: A single agent strikes multiple targets simultaneously. For example, catecholamine excess concurrently provokes arterial hypertension, thrombosis, cardiac arrhythmia, and hyperglycemia.